Predictor Importance Values for paper birch (Betula papyrifera)

Predictor Name	Importance Score	Rank
Annual precipitation (mm)	13.49	35
Mean May-September precipitation (mm)	21.99	8
Mean annual temperature (°C)	18.31	21
Mean May-September temperature (°C)	19.85	15
Mean temperature of coldest month (°C)	20.22	14
Mean temperature of warmest month (°C)	22.23	7
Annual aridity index	11.86	40
Minimum elevation	19.17	16
Maximum elevation	11.09	41
Average elevation	12.91	37
Median elevation	13.06	36
Range of elevation	21.72	10
Elevation coefficient ofvariation	16.42	27
Elevation standard deviation	24.88	3
Annual daylength coefficient of variation	21.28	11
Total available water capacity (cm, to 150 cm)	16.51	26
Total available water supply (cm, to 150 cm)	15.43	28
Depth to water table (cm)	28.32	1
Soil permeability rate (cm/hr)	12.74	38
Soil calcium carbonate (% by weight)	19.01	17
Soil cation-exchange capacity	17.66	22
Soil pH	14.18	31
Soil bulk density (g/cm3)	20.95	12
Organic matter content (% by weight)	16.66	24
Potential soil productivity	25.1	2
Soil erodibility factor, rock fragment free	23.76	5
Soil erosion by wind (tons/acre/year)	18.67	18
Percent soil passing sieve No. 10 (coarse)	23.45	6
Percent soil passing sieve No. 200 (fine)	21.93	9
Percent clay (< 0.002 mm size)	18.38	20
Percent sand (< 0.002 mm size)	24.2	4
Percent silt (< 0.002 mm size)	16.55	25
Percent of texture clayey	14.04	33
Percent of texture loamy	14.9	29
Percent of texture sandy	20.51	13
Percent of texture other	14.1	32
Alfisol (%)	12.1	39
Aridisol (%)	1.02	45
Entisol (%)	8.03	42
Histosol (%)	17.48	23
Inceptisol (%)	18.52	19
Mollisol (%)	13.82	34
Spodosol (%)	14.47	30
Ultisol (%)	6.13	43
Vertisol (%)	2.69	44